The influence of Reynolds number on a plane jet
Article
Article Title | The influence of Reynolds number on a plane jet |
---|---|
ERA Journal ID | 1298 |
Article Category | Article |
Authors | Deo, Ravinesh C. (Author), Mi, Jianchun (Author) and Nathan, Graham J. (Author) |
Journal Title | Physics of Fluids |
Journal Citation | 20 (7), pp. 075108-1 |
Number of Pages | 16 |
Year | 2008 |
Place of Publication | Melville, NY, United States |
ISSN | 1070-6631 |
1089-7666 | |
Digital Object Identifier (DOI) | https://doi.org/10.1063/1.2959171 |
Web Address (URL) | http://pof.aip.org/phfle6/v20/i7/p075108_s1?isAuthorized=no |
Abstract | The present study systematically investigates through experiments the influence of Reynolds number on a plane jet issuing from a radially contoured, rectangular slot nozzle of large aspect ratio. Detailed velocity measurements were performed for a jet exit Reynolds number spanning the range 1500 ≤ Reh ≤ 16 500, where Reh ≡ Ubh/υ with Ub as the momentum-averaged exit mean velocity, h as the slot height, and υ as the kinematic viscosity. Additional centerline measurements were also performed for jets from two different nozzles in the same facility to achieve Reh = 57 500. All measurements were conducted using single hot-wire anemometry to an axial distance (x) of x ≤ 160h. These measurements revealed a significant dependence of the exit and the downstream flows on Reh despite all exit velocity profiles closely approximating a “top-hat” shape. The effect of Reh on both the mean and turbulent fields is substantial for Reh<10 000 but becomes weaker with increasing Reh. The length of the jet’s potential core, initial primary-vortex shedding frequency, and far-field rates of decay and spread all depend on Reh. The local Reynolds number, Rey0.5 ≡ 2Ucy0.5/υ, where Uc and y0.5 are the local centerline velocity and half-width, respectively, are found to scale as Rey0.5 ∼ x1/2. It is also shown that, for Reh ≥ 1500, self-preserving relations of both the turbulence dissipation rate (ε) and smallest scale (η), i.e., ε ∼ Reh3(x/h)−5/2 and η ∼ Reh−3/4(x/h)5/8, become valid for x/h ≥ 20 |
Keywords | plane jet; Reynolds number effect; vortex shedding; jet mixing and entrainment |
ANZSRC Field of Research 2020 | 401201. Aerodynamics (excl. hypersonic aerodynamics) |
401213. Turbulent flows | |
401299. Fluid mechanics and thermal engineering not elsewhere classified | |
Public Notes | Files associated with this item cannot be displayed due to copyright restrictions. |
Byline Affiliations | University of Adelaide |
https://research.usq.edu.au/item/9zqz1/the-influence-of-reynolds-number-on-a-plane-jet
2230
total views14
total downloads4
views this month0
downloads this month